Mechanisms for forming image sensor device

ABSTRACT

Embodiments of mechanisms for forming an image sensor device are provided. The image sensor device includes a semiconductor substrate and a photodetector in the semiconductor substrate. The image sensor device also includes a dielectric layer over the semiconductor substrate, and the dielectric layer has a recess aligned with the photodetector. The image sensor device further includes a filter in the recess of the dielectric layer. In addition, the image sensor device includes a shielding layer between the dielectric layer and the semiconductor substrate and surrounding the filter.

BACKGROUND

The semiconductor integrated circuit (IC) has experienced rapid growth.Technological advances in IC materials and design have producedgenerations of ICs where each generation has smaller and more complexcircuits than the previous generation. In the course of IC evolution,functional density (i.e., the number of interconnected devices per chiparea) has generally increased while geometric size (i.e., the smallestcomponent that can be created using a fabrication process) hasdecreased. Such advances have increased the complexity of processing andmanufacturing ICs. For these advances, similar developments in ICprocessing and manufacturing are needed.

Along with the advantages realized from reducing geometry size,improvements are being made directly to the IC devices. One such ICdevice is an image sensor device. An image sensor device includes apixel array (or grid) for detecting light and recording intensity(brightness) of the detected light. The pixel array responds to thelight by accumulating a charge. The higher the intensity of the lightis, the higher the charge is accumulated in the pixel array. Theaccumulated charge is then used (for example, by other circuitry) toprovide image information for use in a suitable application, such as adigital camera.

However, since the feature sizes continue to decrease, fabricationprocesses continue to become more difficult to perform. Therefore, it isa challenge to form reliable image sensor devices with smaller andsmaller sizes.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the illustrative embodiments andthe advantages thereof, reference is now made to the followingdescriptions taken in conjunction with the accompanying drawings.

FIG. 1 is a top view of an image sensor device, in accordance with someembodiments.

FIG. 2 is an enlarged top view of a pixel region in an image sensordevice, in accordance with some embodiments.

FIG. 3 is a cross-sectional view of an image sensor device, inaccordance with some embodiments.

FIGS. 4A-4E are cross-sectional views of a process for forming an imagesensor device, in accordance with some embodiments.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments of the disclosure arediscussed in detail below. It should be appreciated, however, that thevarious embodiments can be embodied in a wide variety of specificcontexts. The specific embodiments discussed are merely illustrative,and do not limit the scope of the disclosure.

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the disclosure. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are merelyexamples and are not intended to be limiting. Moreover, the performanceof a first process before a second process in the description thatfollows may include embodiments in which the second process is performedimmediately after the first process, and may also include embodiments inwhich additional processes may be performed between the first and secondprocesses. Various features may be arbitrarily drawn in different scalesfor the sake of simplicity and clarity. Furthermore, the formation of afirst feature over or on a second feature in the description thatfollows include embodiments in which the first and second features areformed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact.

Some variations of the embodiments are described. Throughout the variousviews and illustrative embodiments, like reference numbers are used todesignate like elements.

FIG. 1 is a top view of an image sensor device 100, in accordance withsome embodiments. The image sensor device 100 may be a backsideilluminated (BSI) image sensor device. However, it should be appreciatedthat embodiments of the disclosure are not limited thereto. In someother embodiments, the image sensor device 100 is a front sideilluminated (FSI) image sensor device.

In some embodiments, the image sensor device 100 includes an array ofpixel regions 101. The pixel regions 101 may be arranged into a column(for example, C₁ to C_(x)) and a row (for example, R₁ to R_(Y)). Theterm “pixel region” refers to a unit cell containing features (forexample, a photodetector and various circuitry). The unit cell mayinclude various semiconductor devices for converting electromagneticradiation into an electrical signal. Photodetectors in the pixel regions101 may include photodiodes, complimentary metal-oxide-semiconductor(CMOS) image sensors, charged coupling device (CCD) sensors, activesensors, passive sensors, other applicable sensors, or a combinationthereof.

The pixel regions 101 may be designed having various sensor types. Onegroup of pixel regions 101 may be CMOS image sensors, and another groupof pixel regions 101 may be other types of sensors, such as passivesensors. In some embodiments, each pixel region 101 includes aphotodetector, such as a photogate-type photodetector, for recordingintensity or brightness of light (radiation). Each pixel region 101 mayalso include various semiconductor devices, such as various transistors.

Additional circuitry, inputs, and/or outputs may be formed in aperipheral region of the image sensor device 100 and be coupled to thepixel regions 101. The circuitry in the peripheral region provides anoperation environment for the pixel regions 101 and support externalcommunications with the pixel regions 101.

FIG. 2 is an enlarged top view of one of the pixel regions 101 of theimage sensor device 100 on a front surface of a semiconductor substrate(not illustrated in FIG. 2), in accordance with some embodiments. Asshown in FIG. 2, the pixel region 101 includes a photodetector 106. Insome embodiments, the photodetector 106 includes a photodiode forrecording intensity or brightness of light (radiation). The pixel region101 may contain various transistors. For example, the transistorsinclude a transfer transistor 110, a reset transistor 112, asource-follower transistor 114, a select transistor 116, other suitabletransistors, or a combination thereof.

The pixel region 101 may also include various doped regions in thesemiconductor substrate, such as doped regions 118A, 118B, and 120. Thedoped regions 118A, 118B, and 120 serve as source/drain regions of thepreviously mentioned transistors. The doped region 120 is also referredto as a floating diffusion region in some embodiments. The doped region120 is between the transfer transistor 110 and the reset transistor 112,and is one of the source/drain regions for the transfer transistor 110and the reset transistor 112. In some embodiments, a conductive feature131 overlaps a portion of a gate stack of the source-follower transistor114 and connects to the doped region 120.

The image sensor device 100 may also include various isolationstructures 108 formed in the semiconductor substrate to isolate variousregions of the semiconductor substrate. The isolation structures 108prevent leakage currents between various regions. In some embodiments,the isolation structures 108 include dielectric isolation structures.The dielectric isolation structures may be formed by a shallow trenchisolation (STI) technique, a deep trench isolation (DTI) technique,other applicable techniques, or a combination thereof.

In some embodiments, the isolation structures 108 may include dopedisolation structures formed by an implantation technique or diffusiontechnique. In some embodiments, the isolation structures 108 are formedin the pixel region 101 to isolate the photodetector 106, the transfertransistor 110, the reset transistor 112, the source-follower transistor114, and the select transistor 116.

The image sensor device 100 further includes a color filter and a lensdisposed over a back surface of the semiconductor substrate in someembodiments. The color filter and the lens may be aligned with thephotodetector 106. The lens is used to direct or focus the incidentlight. The color filter is designed so that it filters through light ofa predetermined wavelength band. For example, the color filter mayfilter through visible light of a red wavelength band, a greenwavelength band, or a blue wavelength band to the photodetector 106.

In the operation of the image sensor device 100 according to someembodiments, the image sensor device 100 is designed to receiveradiation traveling towards the back surface of the semiconductorsubstrate. The lens disposed over the back surface of the semiconductorsubstrate directs the incident radiation to the correspondingphotodetector 106 in the semiconductor substrate. The incident radiationgenerates electron-hole pairs. When exposed to the incident radiation,the photodetector 106 responds to the incident radiation by accumulatingelectrons. The holes may be trapped by a doped layer over the backsurface of the semiconductor substrate to prevent the recombination ofthe electrons and the holes.

The electrons are transferred from the photodetector 106 to the dopedregion 120 when the transfer transistor 110 is turned on. Through theconnection of the conductive feature 131, the source-follower transistor114 may convert the electrons from the doped region 120 to voltagesignals. The select transistor 116 may allow a single row (or a singlecolumn) of the pixel array to be read by read-out electronics. The resettransistor 112 may act as a switch to reset the doped region 120. Whenthe reset transistor 112 is turned on, the doped region 120 is connectedto a power supply to clear all accumulated electrons.

It should be appreciated that embodiments of the disclosure are notlimited to being the image sensor device 100 shown in FIG. 1 or 2. Insome other embodiments, the image sensor device 100 includes differentconfigurations.

As mentioned above, the lens and the color filter are used to guide theincident light with particular wavelength band to the photodetector.FIG. 3 is a cross-sectional view of the image sensor device 100, inaccordance with some embodiments.

As shown in FIG. 3, the image sensor device 100 includes a dielectricgrid 306 over a semiconductor substrate 300 including one or more pixelregions 101A, 101B, and 101C, in accordance with some embodiments.Similar to the embodiments shown in FIG. 2, each of the pixel regionssuch as 101A, 101B, and 101C includes a photodetector formed in thesemiconductor substrate 300. For example, the pixel regions 101A, 101B,and 101C include photodetectors 106A, 106B, and 106C, respectively. Insome embodiments, the photodetectors 106A, 106B, and 106C includephotodiodes having p-type and n-type doped regions formed in thesemiconductor substrate 300.

As shown in FIG. 3, an anti-reflection coating (ARC) layer 302 and abuffer layer 304 are formed over a surface of the semiconductorsubstrate 300, in accordance with some embodiments. The ARC layer 302 isused to reduce optical reflection from the surface of the semiconductorsubstrate 300 to ensure that most of an incident light enters thephotodetector and is sensed. The ARC layer 302 may be made of a high-kmaterial, a dielectric material, other applicable materials, or acombination thereof. The high-k material may include hafnium oxide,tantalum pentoxide, zirconium dioxide, aluminum oxide, other suitablematerials, or a combination thereof. The dielectric material includes,for example, silicon nitride, silicon oxynitride, other suitablematerials, or a combination thereof. The buffer layer 304 is used as abuffer between the ARC layer 302 and an overlying layer subsequentlyformed. The buffer layer 304 may be made of a dielectric material orother suitable materials. For example, the buffer layer 304 is made ofsilicon oxide, silicon nitride, silicon oxynitride, other applicablematerials, or a combination thereof. In some embodiments, the ARC layerand/or the buffer layer are/is not used.

As shown in FIG. 3, the dielectric grid 306 is formed over the bufferlayer 304, in accordance with some embodiments. The dielectric grid 306includes multiple recesses such as recesses 308A, 308B, and 308C. Insome embodiments, filters such as color filters 310R, 310B, and 310G areformed in the recesses 308A, 308B, and 308C, respectively. The colorfilters 310R, 310B, and 310G may be used to filter through a redwavelength band, a blue wavelength band, and a green wavelength band,respectively.

As shown in FIG. 3, lenses 312A, 312B, and 312C are respectivelydisposed or formed over the color filters 310R, 310B, and 310G, inaccordance with some embodiments. The lenses 312A, 312B, and 312C areused to direct or focus the incident light. The lenses 312A, 312B, and312C may include a microlens array. The lenses 312A, 312B, and 312C maybe made of a high transmittance material. For example, the hightransmittance material includes transparent polymer material (such aspolymethylmethacrylate, PMMA), transparent ceramic material (such asglass), other applicable materials, or a combination thereof.

As shown in FIG. 3, an incident light L₁ is directed by the lens 312Aand enters the color filter 310R in some embodiments. The incident lightL₁ is reflected by the sidewall of the recess 308A and sensed by thephotodetector 106A in the pixel region 101A. In some embodiments, thecolor filter 310R filters through visible light of a red wavelength bandto the photodetector 106A.

However, in some cases, an incident light L₂ may enter the lens 312C andpenetrate through the dielectric grid 306 to a neighboring photodetector106B in the pixel region 101B. The incident light L₂ is not filtered bythe color filter 310G and is sensed by the photodetector 106B but not bythe photodetector 106C. The photodetector may therefore collectnon-filtered signals and a crosstalk problem may occur. As a result, theperformance and the reliability of the image sensor device 100 arelowered. Since the feature size continues to shrink, the problemsmentioned above are exacerbated in some embodiments.

Therefore, it is desirable to find alternative mechanisms for forming animage sensor device to resolve or reduce the problems mentioned above.FIGS. 4A-4E are cross-sectional views of a process for forming an imagesensor device 100′, in accordance with some embodiments. The imagesensor device 100′ may have a configuration similar to the image sensordevice 100 shown in FIGS. 1 and 2.

As shown in FIG. 4A, the semiconductor substrate 300 including the pixelregions 101A, 101B, and 101C are provided. The photodetectors 106A,106B, and 106C are formed in the pixel regions 101A, 101B, and 101C,respectively.

The ARC layer 302 and the buffer layer 304 are formed over thesemiconductor substrate 300, as shown in FIG. 4A. The ARC layer 302 andthe buffer layer 304 may be deposited sequentially over thesemiconductor substrate 300 using a chemical vapor deposition (CVD)process, spin-on process, physical vapor deposition (PVD) process, otherapplicable processes, or a combination thereof. In some otherembodiments, however, one or both of the ARC layer 302 and the bufferlayer 304 are not formed.

As shown in FIG. 4A, a reflective layer 408 is formed over the bufferlayer 304, in accordance with some embodiments. The reflective layer 408may include reflective elements 408A. Each of the reflective elements408A is used to prevent the incident light from entering a neighboringpixel. The crosstalk problems between pixel regions are thus preventedor reduced.

In some embodiments, the reflective layer 408 is made of a reflectivematerial such as a metal material. The reflective layer 408 may be madeof aluminum, silver, copper, titanium, platinum, tungsten, tantalum,tantalum nitride, other suitable materials, or a combination thereof. Insome embodiments, the reflective layer 408 is deposited over the bufferlayer 304 using a suitable deposition process. The suitable processincludes, for example, a PVD process, an electroplating process, a CVDprocess, other applicable processes, or a combination thereof.Afterwards, the reflective layer 408 is patterned using, for example, aphotolithography process and an etching process to form the reflectiveelements 408A.

After the formation of the reflective layer 408, a dielectric layer 406Ais deposited over the reflective layer 408 and the buffer layer 304, asshown in FIG. 4A in accordance with some embodiments. The dielectriclayer 406A may be made of silicon oxide, silicon nitride, siliconoxynitride, or other suitable materials. A CVD process or the like maybe performed to form the dielectric layer 406A. In some embodiments, aplanarization process is performed to provide a substantially planar topsurface of the dielectric layer 406A. The planarization process mayinclude a chemical mechanical polishing (CMP) process, a grindingprocess, an etching process, other applicable processes, or acombination thereof. In some embodiments, the dielectric layer 406Asurrounds the reflective elements 408A, as shown in FIG. 4A.

Afterwards, a shielding layer 410 is deposited over the dielectric layer406A, as shown in FIG. 4B in accordance with some embodiments. Theshielding layer 410 may be used to reflect and/or absorb the incidentlight. Therefore, the incident light is blocked from penetrating throughthe shielding layer 410. In some embodiments, the shielding layer 410 isconfigured to completely block the incident light. The transmittance ofthe shielding layer 410 may be in a range from about 0 to about 0.20.

In some embodiments, the shielding layer 410 is made of a metal materialor a metal-containing material. The metal material or themetal-containing material includes, for example, aluminum, silver,copper, titanium, platinum, tungsten, tantalum, tantalum nitride, othersuitable materials, or a combination thereof. In some embodiments, theshielding layer 410 and the reflective layer 408 are made of the samematerial. In some other embodiments, the shielding layer 410 and thereflective layer 408 are made of different materials.

Embodiments of the disclosure have many variations. In some embodiments,the shielding layer 410 is made of a semiconductor material. Thesemiconductor material may have high absorption of visible (and/orinfrared) light. For example, the shielding layer 410 may be made ofblack silicon or other suitable semiconductor materials. The blacksilicon may include a needle-shaped surface structure where needles aremade of single-crystal or polycrystal silicon. In some otherembodiments, the shielding layer 410 may be made of a polymer materialor a ceramic material capable of reflecting and/or absorbing theincident light.

The shielding layer 410 may be deposited over the dielectric layer 406Ausing a PVD process, CVD process, spin-on process, other suitableprocesses, or a combination thereof. In some embodiments, the shieldinglayer 410 is thinner than the reflective layer 408. The shielding layer410 may have a thickness in a range from about 10 nm to about 500 nm.However, embodiments of the disclosure are not limited thereto. In someother embodiments, the shielding layer 410 is not thinner than thereflective layer 408. Alternatively, in some embodiments, the shieldinglayer 410 includes a stack of multiple layers. The multiple layers maybe a number of the same layers. Alternatively, some or all of themultiple layers are different layers.

After the formation of the shielding layer 410, a dielectric layer 406Bis deposited over the shielding layer 410, as shown in FIG. 4B inaccordance with some embodiments. In some embodiments, the materials ofthe dielectric layer 406B and the shielding layer 410 are different fromeach other. The dielectric layer 406B may be made of silicon oxide,silicon nitride, silicon oxynitride, other suitable materials, or acombination thereof. The dielectric layer 406B may be deposited using aCVD process, a spin-on process, a PVD process, other applicableprocesses, or a combination thereof. In some embodiments, the materialsof the dielectric layers 406B and 406A are the same. In some otherembodiments, the materials of the dielectric layers 406B and 406A aredifferent from each other. The dielectric layer 406B may have athickness larger than that of the dielectric layer 406A. In someembodiments, a planarization process is performed on the dielectriclayer 406B to provide a substantially planar top surface of thedielectric layer 406B. The planarization process includes, for example,a CMP process, a grinding process, an etching process, other applicableprocesses, or a combination thereof.

As shown in FIG. 4C, the dielectric layer 406B is partially removed toform the recesses 308A, 308B, and 308C, in accordance with someembodiments. In some embodiments, a photolithography process and anetching process are performed to form the recesses 308A, 308B, and 308C.The shielding layer 410 may also function as an etch stop layer in theetching process for forming the recesses 308A, 308B, and 308C. As shownin FIG. 4C, the shielding layer 410 is exposed by the recesses 308A,308B, and 308C.

Afterwards, the exposed portions of the shielding layer 410 are removedsuch that the recesses 308A, 308B, and 308C expose the dielectric layer406A, as shown in FIG. 4D in accordance with some embodiments. Anetching process may be performed to remove the exposed portion of theshielding layer 410. As a result, a dielectric grid constructed by thepatterned dielectric layer 406B is formed, as shown in FIG. 4D. In someembodiments, each of the recesses 308A, 308B, and 308C is aligned withthe photodetectors 106A, 106B, and 106C, respectively.

As shown in FIG. 4E, filters such as the color filters 310R, 310B, and310G are respectively formed in the recesses of the dielectric layer406B (or dielectric grid), in accordance with some embodiments. As shownin FIG. 4E, the shielding layer 410 surrounds the color filters 310R,310B, and 310G. The color filters 310R, 310B, and 310G may be made of adye-based polymer (or a pigment-based polymer). In some embodiments, afirst filter film is deposited over the dielectric layer 406B to fillthe recesses 308A, 308B, and 308C using, for example, a spin-on processor other applicable processes. The first filter film may also be aphotoresist layer. Therefore, exposure and development operations maythen be performed to pattern the first filter film such that the firstfilter film remains in one of the recesses, such as the recess 308A. Asa result, the color filter 310R is formed. Similarly, the color filters310B and 310G may be formed sequentially by using similar methods.

In some embodiments, the color filters 310R, 310B, and 310G haveprotruding portions 311R, 311B, and 311G, respectively. Each of theprotruding portions 311R, 311B, and 311G protrudes from a bottom surface407 of the dielectric layer 406B. The protruding portions 311R, 311B,and 311G are surrounded by the shielding layer 410, as shown in Fig. 4Ein accordance with some embodiments. In some embodiments, a bottom ofthe shielding layer 410 is substantially coplanar with bottoms of thecolor filters 310R, 310B, and 310G, as shown in FIG. 4E.

After the formation of the color filters, the lenses 312A, 312B, and312C are respectively formed over the color filters 310R, 310B, 310G, asshown in FIG. 4E in accordance with some embodiments. As shown in FIG.4E, an incident light L₃ is directed by the lens 312A and enters thecolor filter 310R in some embodiments. The incident light L₃ isreflected by the sidewall of the recess 308A and sensed by thephotodetector 106A in the pixel region 101A. An incident light L₄,similar to the incident light L₂ shown in FIG. 3, is blocked by theshielding layer 410 from entering the pixel region 101B adjacent to thepixel region 101C. Therefore, substantially no non-filtered signals aresensed by the photodetectors. The crosstalk problem is also prevented orsignificantly reduced. The performance and reliability of the imagesensor device 100′ are improved.

Embodiments of mechanisms for forming an image sensor device areprovided. A shielding layer is formed between color filters of the imagesensor device. Due to the shielding layer, substantially no non-filteredsignals enter the photodetectors, and the crosstalk problem is preventedor significantly reduced. The yield and performance of the image sensordevice are therefore improved.

In accordance with some embodiments, an image sensor device is provided.The image sensor device includes a semiconductor substrate and aphotodetector in the semiconductor substrate. The image sensor devicealso includes a dielectric layer over the semiconductor substrate, andthe dielectric layer has a recess aligned with the photodetector. Theimage sensor device further includes a filter in the recess of thedielectric layer. In addition, the image sensor device includes ashielding layer between the dielectric layer and the semiconductorsubstrate and surrounding the filter.

In accordance with some embodiments, an image sensor device is provided.The image sensor device includes a semiconductor substrate having afirst pixel region and a second pixel region. The image sensor devicealso includes a first photodetector and a second photodetector in thefirst pixel region and the second pixel region, respectively. The imagesensor device further includes a dielectric layer over the semiconductorsubstrate, and the dielectric layer has a first recess and a secondrecess aligned with the first photodetector and the secondphotodetector, respectively. In addition, the image sensor deviceincludes a first filter and a second filter in the first recess and thesecond recess, respectively. The image sensor device also includes ashielding layer between the dielectric layer and the semiconductorsubstrate and surrounding the first filter and the second filter.

In accordance with some embodiments, a method for forming an imagesensor device is provided. The method includes forming a photodetectorin a semiconductor substrate and forming a shielding layer over thesemiconductor substrate. The method also includes forming a dielectriclayer over the shielding layer and partially removing the dielectriclayer to form a recess. The method further includes partially removingthe shielding layer through the recess and forming a filter in therecess after the shielding layer is partially removed.

Although the embodiments and their advantages have been described indetail, it should be understood that various changes, substitutions, andalterations can be made herein without departing from the spirit andscope of the embodiments as defined by the appended claims. Moreover,the scope of the present application is not intended to be limited tothe particular embodiments of the process, machine, manufacture,composition of matter, means, methods, and steps described in thespecification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps. In addition, each claim constitutes a separateembodiment, and the combination of various claims and embodiments arewithin the scope of the disclosure.

What is claimed is:
 1. An image sensor device, comprising: a semiconductor substrate; a photodetector in the semiconductor substrate; a dielectric layer over the semiconductor substrate, wherein the dielectric layer has a recess aligned with the photodetector; a filter in the recess of the dielectric layer; and a shielding layer between the dielectric layer and the semiconductor substrate and surrounding the filter.
 2. The image sensor device as claimed in claim 1, wherein the filter has a protruding portion protruding from a bottom surface of the dielectric layer, and the shielding layer surrounds the protruding portion of the filter.
 3. The image sensor device as claimed in claim 1, wherein a bottom of the shielding layer is substantially coplanar with a bottom of the filter.
 4. The image sensor device as claimed in claim 1, wherein the shielding layer comprises a metal material.
 5. The image sensor device as claimed in claim 1, further comprising a lens over the photodetector.
 6. The image sensor device as claimed in claim 1, further comprising an anti-reflection layer between the semiconductor substrate and the shielding layer.
 7. The image sensor device as claimed in claim 1, further comprising: a reflective element over the semiconductor substrate; and a second dielectric layer surrounding the reflective element, wherein the second dielectric layer is between the semiconductor susbtrate and the dielectric layer.
 8. The image sensor device as claimed in claim 7, wherein materials of the reflective element and the shielding layer are the same.
 9. The image sensor device as claimed in claim 7, further comprising: a black level correction region in the semiconductor substrate; and a shielding element over the black level correction region, wherein materials of the shielding element and the reflective element are the same.
 10. The image sensor device as claimed in claim 7, wherein the shielding layer is thinner than the reflective element.
 11. An image sensor device, comprising: a semiconductor substrate having a first pixel region and a second pixel region; a first photodetector and a second photodetector in the first pixel region and the second pixel region, respectively; a dielectric layer over the semiconductor substrate, wherein the dielectric layer has a first recess and a second recess aligned with the first photodetector and the second photodetector, respectively; a first filter and a second filter in the first recess and the second recess, respectively; and a shielding layer between the dielectric layer and the semiconductor substrate and surrounding the first filter and the second filter.
 12. The image sensor device as claimed in claim 11, wherein the first filter and the second filter have protruding portions protruding from a bottom surface of the dielectric layer, and the shielding layer surrounds the protruding portions.
 13. The image sensor device as claimed in claim 11, wherein a bottom of the shielding layer is substantially coplanar with bottoms of the first filter and the second filter.
 14. The image sensor device as claimed in claim 11, wherein the shielding layer comprises a metal material, a polymer material, a semiconductor material, a ceramic material, or a combination thereof.
 15. The image sensor device as claimed in claim 11, wherein a thickness of the shielding layer is in a range from about 10 nm to about 500 nm.
 16. A method for forming an image sensor device, comprising: forming a photodetector in a semiconductor substrate; forming a shielding layer over the semiconductor substrate; forming a dielectric layer over the shielding layer; partially removing the dielectric layer to form a recess; partially removing the shielding layer through the recess; and forming a filter in the recess after the shielding layer is partially removed.
 17. The method for forming an image sensor device as claimed in claim 16, wherein the shielding layer functions as an etch stop layer when the recess is formed.
 18. The method for forming an image sensor device as claimed in claim 16, further comprising forming an anti-reflection layer over the semiconductor substrate before the shielding layer is formed.
 19. The method for forming an image sensor device as claimed in claim 16, further comprising: forming a reflective element over the semiconductor substrate before the shielding layer is formed; and forming a second dielectric layer surrounding the reflective layer before the shielding layer is formed.
 20. The method for forming an image sensor device as claimed in claim 16, further comprising forming a lens over the photodetector. 